1. Field of the Invention
This invention relates generally to suspensions of trailers, and more particularly to a suspension system for a trailer that has a bed that can be lowered to the ground.
2. Description of Related Art
Utility trailers are commonly coupled behind self-propelled vehicles and used to haul bulky and/or heavy objects. A typical trailer includes a frame supported on wheels and a platform called a “bed” on which a load is placed. Some trailers include ramps for loading and unloading cargo. Other trailers are designed to be tipped to facilitate loading and unloading.
Trailers are also known that have beds that can be lowered to the ground. An example of such a trailer is disclosed in Stringer, U.S. Pat. No. 6,273,435, which teaches a trailer that includes a bed that is attached to the frame with a hydraulic slider that functions to raise and lower the bed.
Behr, U.S. Pat. No. 5,536,131, teaches a utility trailer that includes a bed that is pivotally attached to a frame of the trailer. A hand winch is used to manually raise and lower the bed in a generally vertical direction.
Shiels, U.S. Pat. No. 4,673,328, teaches a trailer with a lift/tilt-bed. The trailer includes four pivotal tracks that function to guide the bed from the lowered to the raised position.
Various other prior art references teach similar trailers, including Bartel, U.S. Pat. No. 6,142,496, Wellman, U.S. Pat. No. 5,810,544, Nowell et al., U.S. Pat. No. 5,765,859, Rogge et al., U.S. Pat. No. 5,474,416, Celli, U.S. Pat. No. 4,685,855, and Fowler, U.S. Pat. No. 4,154,352.
The above-described patents are hereby incorporated by reference in full.
In many wheeled vehicles, each wheel is suspended via a suspension system that dampens roughness of a surface under the wheel as the wheel moves over the surface. In general, a trailer is a vehicle adapted to be pulled (i.e., towed) behind a self-propelled vehicle. Known suspension systems for trailers include spring-mounted axles. In a typical trailer with a spring-mounted axle, the axle extends between opposite sides of the trailer and passes under a bed of the trailer. Located under the bed, the axle prevents the bed from being lowered to the ground.
It would be beneficial to have a suspension system for a wheel of a vehicle that does not extend under the vehicle. Such a suspension system would allow, for example, the construction of a trailer having a bed that can be lowered to the ground to facilitate loading objects on the bed and unloading objects from the bed.